In mobile communications networks, it may be desirable to share core network (CN) node resources among radio access nodes, such as UMTS radio network controllers (RNCs) and GSM base station controllers (BSCs). Conventionally, radio access nodes were restricted to a single core network node. As a result of this strict hierarchy, core node resources were inefficiently used.
3GPP TS 23.236 defines technical requirements for A/Iu-flex, a proposal where radio access nodes, such as RNCs and BSCs, can select any core network node, such as a serving GPRS support node (SGSN) or mobile switching center (MSC) that serves a specific geographic area, referred to as a pool area. The group of CN nodes that serve a pool area is referred to as the MSC pool or the SGSN pool. Allowing access nodes to select from plural CN nodes within a pool area increases the efficiency of utilization of CN node resources.
One problem with the architecture proposed in 3GPP TS 23.236 is that it requires that the intelligence for selecting the CN node to be in the access node, i.e., in the BSC or RNC. However, legacy BSCs and RNCs may not have the capability to perform such selection. In light of the number of BSCs or RNCs in a network, upgrading all of the BSCs or RNCs in a network may be cost-prohibitive. Another problem with the architecture proposed in TS 23.236 is that it does not specify a load-balancing algorithm for balancing the load between available CN nodes. Instead, TS 23.236 indicates that the load-balancing algorithm is “implementation specific.”
3GPP TR 23.823 describes an architecture where the NAS node selection function is located above the BSC/RNC. However, like TS 23.236, TS 23.823 indicates that the load-balancing algorithm is implementation specific. In addition, TR 23.823 indicates that the NNSF can be located in a stand-alone intermediary node or co-located with another node, but does not specify the node type with which the NNSF can be co-located.
Accordingly, in light of these shortcomings, there exists a need for methods, systems, and computer readable media for providing non-access stratum (NAS) node selection function with core network (CN) node bearer-circuit availability monitoring and availability-based load sharing.